I took my '88 4.3L out for a cruise today before storing it and had
overheating problems. So I brought it home and hooked it up to the
flusher. If I pull the inlet hose on the thermostat housing there is
water when it's running. So I pulled the thermostat housing expecting
to find a thermostat in the intake manifold, but there isn't one
there. Rather there seems to be one built into the housing that can't
be changed? I must be missing something, right?

If it's anything like a merc the housing is two pieces.

"Jim" wrote in message
om...
I took my '88 4.3L out for a cruise today before storing it and had
overheating problems. So I brought it home and hooked it up to the
flusher. If I pull the inlet hose on the thermostat housing there is
water when it's running. So I pulled the thermostat housing expecting
to find a thermostat in the intake manifold, but there isn't one
there. Rather there seems to be one built into the housing that can't
be changed? I must be missing something, right?

"Lawrence James" wrote in message thlink.net...
If it's anything like a merc the housing is two pieces.

That's what I first thought too, but this looks like it's all one
casting. Maybe I need to tap it little to see if it seperates, but it
sure doesn't look like it.

If it separates after tapping, you have cracked it in two, since it is one piece. The thermostat is secured in the water distribution
manifold with a retaining ring. The thermostat sits up against a ledge or counterbore. The retaining ring then goes in a groove in the
manifold to keep it from dropping down. To remove, turn the manifold upside down and pry the ring out. You will the be able to remove the
thermostat. If you need a diagram, look at page 5-11 of the OMC Cobra manual.

Jim wrote:

"Lawrence James" wrote in message thlink.net...
If it's anything like a merc the housing is two pieces.

That's what I first thought too, but this looks like it's all one
casting. Maybe I need to tap it little to see if it seperates, but it
sure doesn't look like it.

http://216.37.204.206/Actionsports/O...pe=13&A=11&B=6 hear
is a parts diagram the thermostate is #56 $15.99 . the only ring I see
below it is an o-ring looks to me as if it pops up or screws out. My book
don't go into any real detail, all it tells u is to drain the system, (Seloc
8-15 in the 1985 to 1995 OMC Cobra & King Cobra stern drive manual). I don't
see how taking the intake manifold off will help much just to turn it upside
down and hope it falls out, seams like alot of work to me. Of course I never
replaced one in a boat but I would still try to pry it out insted of going
through all that trouble. If its in a well then try some c-clip plyers, if
not just pry it up with a screw driver. it may be garbage when u get it out
but a new one that looks to just drop in @ only $16 is insurance enough for
me. But then again it isn't my boat. Good luck.


"Jim" wrote in message
om...
I took my '88 4.3L out for a cruise today before storing it and had
overheating problems. So I brought it home and hooked it up to the
flusher. If I pull the inlet hose on the thermostat housing there is
water when it's running. So I pulled the thermostat housing expecting
to find a thermostat in the intake manifold, but there isn't one
there. Rather there seems to be one built into the housing that can't
be changed? I must be missing something, right?

I saw this parts breakdown a couple days ago, but I'm still confused.
The thermostat shown in this picture is not on my engine. If it was
there, it's been removed. There is one in the top of the thermostat
housing that sure looks like it was cast with it in there (which seems
like a very odd thing to do). It seems to control the water flow to the
exhaust manifolds.

This brings me to a flow question. It *looks* like fresh water is pumped
up from the outdrive to the thermostat housing. The water pump on the
engine picks that up, pumps it through the block/heads/intake and back
to the thermostat housing. Then is *looks* like the thermostat in the
top of the housing opens at whatever temp to let the water out to the
exhaust manifolds to be replaced by fresh water. Does this seem right?

Wildest Dream wrote:
http://216.37.204.206/Actionsports/O...pe=13&A=11&B=6 hear
is a parts diagram the thermostate is #56 $15.99 . the only ring I see
below it is an o-ring looks to me as if it pops up or screws out. My book
don't go into any real detail, all it tells u is to drain the system, (Seloc
8-15 in the 1985 to 1995 OMC Cobra & King Cobra stern drive manual). I don't
see how taking the intake manifold off will help much just to turn it upside
down and hope it falls out, seams like alot of work to me. Of course I never
replaced one in a boat but I would still try to pry it out insted of going
through all that trouble. If its in a well then try some c-clip plyers, if
not just pry it up with a screw driver. it may be garbage when u get it out
but a new one that looks to just drop in @ only $16 is insurance enough for
me. But then again it isn't my boat. Good luck.


"Jim" wrote in message
om...

I took my '88 4.3L out for a cruise today before storing it and had
overheating problems. So I brought it home and hooked it up to the
flusher. If I pull the inlet hose on the thermostat housing there is
water when it's running. So I pulled the thermostat housing expecting
to find a thermostat in the intake manifold, but there isn't one
there. Rather there seems to be one built into the housing that can't
be changed? I must be missing something, right?

I had to think about this for a few minutes. So "water distribution
manifold" = "thermostat housing". right? And there is a ring under the
thermostat sitting in the top of the housing that can be pried out to
remove the thermostat?

Jim Kelly wrote:

If it separates after tapping, you have cracked it in two, since it is one piece. The thermostat is secured in the water distribution
manifold with a retaining ring. The thermostat sits up against a ledge or counterbore. The retaining ring then goes in a groove in the
manifold to keep it from dropping down. To remove, turn the manifold upside down and pry the ring out. You will the be able to remove the
thermostat. If you need a diagram, look at page 5-11 of the OMC Cobra manual.

Jim wrote:


"Lawrence James" wrote in message thlink.net...

If it's anything like a merc the housing is two pieces.

That's what I first thought too, but this looks like it's all one
casting. Maybe I need to tap it little to see if it seperates, but it
sure doesn't look like it.

That is correct, the water distribution manifold takes the place of the thermostat housing used on the automotive version of this engine. I am
NOT referring to, or suggesting that you need to remove, the intake manifold.

In the automotive version, the thermostat fits in a slight counterbore in the top of the intake manifold. The thermostat housing is bolted on
top. In OMC's conversion, a water distribution manifold is substituted for the thermostat housing and a marine thermostat is located in a
counterbore in this housing. The referenced ring fits in a groove after the thermostats is installed. Remove this ring and the thermostat will
come out.

You are also correct in your analysis of the water flow. The water distribution manifold and relocated thermostat are necessary since, unlike an
automotive engine, the exhaust manifolds must be cooled regardless of thermostat state.



Jim wrote:

I had to think about this for a few minutes. So "water distribution
manifold" = "thermostat housing". right? And there is a ring under the
thermostat sitting in the top of the housing that can be pried out to
remove the thermostat?

Jim Kelly wrote:

If it separates after tapping, you have cracked it in two, since it is one piece. The thermostat is secured in the water distribution
manifold with a retaining ring. The thermostat sits up against a ledge or counterbore. The retaining ring then goes in a groove in the
manifold to keep it from dropping down. To remove, turn the manifold upside down and pry the ring out. You will the be able to remove the
thermostat. If you need a diagram, look at page 5-11 of the OMC Cobra manual.

Jim wrote:


"Lawrence James" wrote in message thlink.net...

If it's anything like a merc the housing is two pieces.

That's what I first thought too, but this looks like it's all one
casting. Maybe I need to tap it little to see if it seperates, but it
sure doesn't look like it.

Who said anything about removing the intake manifold? If you re-read the reply,
the words before "manifold" are "water distribution".

Wildest Dream wrote:

http://216.37.204.206/Actionsports/O...pe=13&A=11&B=6 hear
is a parts diagram the thermostate is #56 $15.99 . the only ring I see
below it is an o-ring looks to me as if it pops up or screws out. My book
don't go into any real detail, all it tells u is to drain the system, (Seloc
8-15 in the 1985 to 1995 OMC Cobra & King Cobra stern drive manual). I don't
see how taking the intake manifold off will help much just to turn it upside
down and hope it falls out, seams like alot of work to me. Of course I never
replaced one in a boat but I would still try to pry it out insted of going
through all that trouble. If its in a well then try some c-clip plyers, if
not just pry it up with a screw driver. it may be garbage when u get it out
but a new one that looks to just drop in @ only $16 is insurance enough for
me. But then again it isn't my boat. Good luck.

"Jim" wrote in message
om...
I took my '88 4.3L out for a cruise today before storing it and had
overheating problems. So I brought it home and hooked it up to the
flusher. If I pull the inlet hose on the thermostat housing there is
water when it's running. So I pulled the thermostat housing expecting
to find a thermostat in the intake manifold, but there isn't one
there. Rather there seems to be one built into the housing that can't
be changed? I must be missing something, right?

Jim wrote in :

I saw this parts breakdown a couple days ago, but I'm still confused.
The thermostat shown in this picture is not on my engine. If it was
there, it's been removed. There is one in the top of the thermostat
housing that sure looks like it was cast with it in there (which seems
like a very odd thing to do).

If this is anything like my Volvo Penta 4.3 (and I believe it is since the
Volvo Penta was derived from the OMC Cobra) there is a retaining ring, its
just very hard to see. I had the same thought as you, that the thermostat
looked like it was cast in place. But I also knew that this was unlikely,
so I searched for what I figured must be there, a retaining ring. Couldn't
find it, so I took the whole piece to my friendly marine shop. When I
asked the counter guy how to get the thermostat out, he said "there's a
retaining ring." He took a tool with a point akin to a dentist's pick and
inserted into a groove just next to the thermostat which I hadn't seen
before. Probably obscured by corrision/debris. The ring is rubber and he
slipped the "pick" under and behind it and lifted the ring out in about 5
seconds. I felt pretty stupid but grateful. The thermostat pulled right out
and the new one dropped right in. The ring was in perfect shape and the
shop didn't even want to sell me a new one, so we popped it back in and was
done. Bolted the housing back on the engine and was in business.